U.S. patent number 7,749,882 [Application Number 11/509,441] was granted by the patent office on 2010-07-06 for packaged microelectronic devices and methods for manufacturing packaged microelectronic devices.
This patent grant is currently assigned to Micron Technology, Inc.. Invention is credited to Tongbi Jiang, Young Do Kweon.
United States Patent |
7,749,882 |
Kweon , et al. |
July 6, 2010 |
Packaged microelectronic devices and methods for manufacturing
packaged microelectronic devices
Abstract
Microelectronic devices and method of forming a plurality of
microelectronic devices on a semiconductor workpiece are disclosed
herein. One such method includes placing a plurality of first
interconnect elements on a side of a semiconductor workpiece,
forming a layer on the side of the workpiece, reshaping the first
interconnect elements by heating the first interconnect elements,
and coupling a first portion of a plurality of individual second
interconnect elements to corresponding first interconnect elements
with a second portion of the individual second interconnect
elements exposed.
Inventors: |
Kweon; Young Do (Boise, ID),
Jiang; Tongbi (Boise, ID) |
Assignee: |
Micron Technology, Inc. (Boise,
ID)
|
Family
ID: |
39197206 |
Appl.
No.: |
11/509,441 |
Filed: |
August 23, 2006 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080050901 A1 |
Feb 28, 2008 |
|
Current U.S.
Class: |
438/597;
257/E23.179; 438/127; 257/E23.001; 257/684; 438/108; 257/678;
438/110; 257/E23.116 |
Current CPC
Class: |
H01L
24/18 (20130101); H01L 24/81 (20130101); H01L
21/78 (20130101); H01L 23/3114 (20130101); H01L
21/566 (20130101); H01L 24/742 (20130101); H01L
24/94 (20130101); H01L 24/12 (20130101); H01L
24/16 (20130101); H01L 24/11 (20130101); H01L
21/4853 (20130101); H01L 23/544 (20130101); H01L
23/49816 (20130101); H01L 24/13 (20130101); H01L
24/14 (20130101); H01L 2224/05599 (20130101); H01L
2224/05001 (20130101); H01L 2924/014 (20130101); H01L
21/563 (20130101); H01L 2924/01006 (20130101); H01L
2224/05008 (20130101); H01L 2224/11013 (20130101); H01L
24/05 (20130101); H01L 2224/13022 (20130101); H01L
2924/01005 (20130101); H01L 2924/00013 (20130101); H01L
2924/00014 (20130101); H01L 2224/05571 (20130101); H01L
2224/7598 (20130101); H01L 2223/54453 (20130101); H01L
2924/01082 (20130101); H01L 2224/1183 (20130101); H01L
2224/05026 (20130101); H01L 2224/274 (20130101); H01L
2224/131 (20130101); H01L 2924/12042 (20130101); H01L
2224/1184 (20130101); H01L 2224/0401 (20130101); H01L
2924/01018 (20130101); H01L 2924/14 (20130101); H01L
2223/54486 (20130101); H01L 2924/01033 (20130101); H01L
2224/13082 (20130101); H01L 2224/16237 (20130101); H01L
2224/05569 (20130101); H01L 2223/54426 (20130101); H01L
2224/11015 (20130101); H01L 2224/16 (20130101); H01L
2224/0557 (20130101); H01L 2224/13099 (20130101); H01L
2924/181 (20130101); H01L 2924/384 (20130101); H01L
2224/13099 (20130101); H01L 2924/00014 (20130101); H01L
2924/00013 (20130101); H01L 2224/13099 (20130101); H01L
2924/181 (20130101); H01L 2924/00 (20130101); H01L
2924/12042 (20130101); H01L 2924/00 (20130101); H01L
2924/00014 (20130101); H01L 2224/05599 (20130101); H01L
2224/131 (20130101); H01L 2924/014 (20130101) |
Current International
Class: |
H01L
21/44 (20060101) |
Field of
Search: |
;438/108,110,127,597
;257/678,684,E23.001,E23.116,E23.179 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Bijnen et al., "Back-side alignment strategy decouples process from
alignment and achieves leading edge overlay performance," Feb.
2006, Microelectronic Engineering, vol. 83, pp. 647-650. cited by
examiner.
|
Primary Examiner: Ghyka; Alexander G
Assistant Examiner: Chang; Leonard
Attorney, Agent or Firm: Perkins Coie LLP
Claims
We claim:
1. A method of forming a plurality of microelectronic devices on a
semiconductor workpiece having a plurality of microelectronic dies,
the method comprising: attaching a plurality of first solder ball
interconnect elements on corresponding terminals of the
semiconductor workpiece; molding a protective layer onto the
workpiece with the layer covering only a portion of individual
first solder ball interconnect elements; reconfiguring the first
solder ball interconnect elements without removing material from
the first solder ball interconnect elements, such that a top
surface of the plurality of first solder ball interconnect elements
located opposite the corresponding terminals is reconfigured to
include a flat surface spaced apart from the protective layer; and
after reconfiguring the first solder ball interconnect elements,
attaching a plurality of second solder ball interconnect elements
on the flat surface of corresponding first solder ball interconnect
elements.
2. The method of claim 1 wherein reconfiguring the first solder
ball interconnect elements comprises heating the first solder ball
interconnect elements.
3. The method of claim 1, further comprising forming an alignment
feature on the workpiece before reconfiguring the first solder ball
interconnect elements.
4. The method of claim 1, wherein reconfiguring the first solder
ball interconnect elements comprises reshaping the first solder
ball interconnect elements without grinding the first solder ball
interconnect elements.
5. The method of claim 1 wherein the semiconductor workpiece
comprises a first side and a second side opposite the first side,
and wherein the method further comprises: marking the first side of
the workpiece with a first alignment feature; and placing a second
alignment mark on the protective layer.
6. The method of claim 1 wherein: attaching the plurality of first
solder ball interconnect elements comprises placing the plurality
of first solder ball interconnect elements on a side of a
semiconductor workpiece; reconfiguring the first solder ball
interconnect elements comprises reshaping the first solder ball
interconnect elements by heating the first solder ball interconnect
elements; and attaching the plurality of second solder ball
interconnect elements on corresponding first solder ball
interconnect elements comprises coupling the second solder ball
interconnect elements to corresponding first solder ball
interconnect elements.
7. The method of claim 6 wherein: the semiconductor workpiece
comprises a redistribution structure on the dies, the
redistribution structure including a plurality of terminals;
attaching the first solder ball interconnect elements on the
workpiece comprises forming the first solder ball interconnect
elements on corresponding terminals of the redistribution
structure; the first solder ball interconnect elements individually
comprise a proximal end at the side of the workpiece and a distal
end opposite the proximal end; reconfiguring the first solder ball
interconnect elements comprises forming the flat surface at the
distal end of the individual first solder ball interconnect
elements; coupling the second solder ball interconnect elements
comprises attaching the second solder ball interconnect elements to
the flat surfaces of the corresponding first solder ball
interconnect elements; and the method further comprises (a) cutting
the semiconductor workpiece to separate the dies after coupling the
second solder ball interconnect elements, and (b) attaching a
separated die to a support member with the second solder ball
interconnect elements attached to corresponding pads on the support
member.
8. The method of claim 6 wherein: the first solder ball
interconnect elements individually comprise a proximal end at the
side of the workpiece and a distal end opposite the proximal end;
and reconfiguring the first solder ball interconnect elements
comprises forming the flat surface at the distal end of the first
solder ball interconnect elements.
9. The method of claim 6 wherein reconfiguring the first solder
ball interconnect elements comprises reconfiguring the first solder
ball interconnect elements without removing material from the first
solder ball interconnect elements.
10. The method of claim 6 wherein reconfiguring the first solder
ball interconnect elements comprises reconfiguring the first solder
ball interconnect elements without removing material from the
layer.
11. The method of claim 6 wherein: the semiconductor workpiece
comprises a redistribution structure on the dies, the
redistribution structure including a plurality of terminals; and
attaching the first solder ball interconnect elements on the
workpiece comprises forming the first solder ball interconnect
elements on corresponding terminals of the redistribution
structure.
12. The method of claim 6 wherein: the plurality of dies have an
integrated circuit and a plurality of terminals operably coupled to
the integrated circuit; and attaching the first solder ball
interconnect elements on the workpiece comprises forming the first
solder ball interconnect elements on corresponding terminals of the
dies.
13. The method of claim 6 wherein: the plurality of dies having an
integrated circuit and a plurality of terminals operably coupled to
the integrated circuit; attaching the first solder ball
interconnect elements on the workpiece comprises forming the first
solder ball interconnect elements on the side of the workpiece with
the first solder ball interconnect elements electrically connected
to corresponding terminals on the dies; and the method further
comprises cutting the workpiece to separate the dies after coupling
the detached second solder ball interconnect elements.
14. The method of claim 6 wherein: forming the layer comprises
constructing the layer with an end portion of the first solder ball
interconnect elements projecting a first distance from the layer;
and reconfiguring the first solder ball interconnect elements
comprises reconfiguring the first solder ball interconnect elements
with the end portion of the first solder ball interconnect elements
projecting a second distance from the layer, the second distance
being less than the first distance.
15. The method of claim 1 wherein reconfiguring the first solder
ball interconnect elements without removing material from the first
solder ball interconnect elements comprises heating the first
solder ball interconnect elements and contacting the first solder
ball interconnect elements with a press.
16. A method of forming microelectronic devices on a semiconductor
workpiece, comprising: attaching first solder ball interconnect
elements to terminals of the semiconductor workpiece; depositing
mold compound onto a surface of the semiconductor workpiece;
clamping the semiconductor workpiece in a mold, the mold comprising
a first mold portion having a compressible release tape configured
to contact the mold compound and deform around a portion of the
first solder ball interconnect elements, and a second mold portion
configured to contact an opposite side of the semiconductor
workpiece, wherein clamping the semiconductor workpiece in the mold
comprises spreading the mold compound across the surface of the
semiconductor workpiece to form a protective layer on the
workpiece, and wherein the first solder ball interconnect elements
protrude from the protective layer; reconfiguring the first solder
ball interconnect elements without removing material from the first
solder ball elements to have a flat top surface spaced apart from
an exposed surface of the protective layer in a different plane;
after reconfiguring the first solder ball interconnect elements,
attaching second solder ball interconnect elements on the flat
surface of the first solder ball interconnect elements.
Description
TECHNICAL FIELD
The present disclosure is related to packaged microelectronic
devices and methods for manufacturing packaged microelectronic
devices.
BACKGROUND
Processors, memory devices, imagers and other types of
microelectronic devices are often manufactured on semiconductor
workpieces or other types of workpieces. In a typical application,
several individual dies (e.g., devices) are fabricated on a single
workpiece using sophisticated and expensive equipment and
processes. Individual dies generally include an integrated circuit
and a plurality of bond-pads coupled to the integrated circuit. The
bond-pads provide external electrical contacts on the die through
which supply voltage, signals, etc., are transmitted to and from
the integrated circuit. The bond-pads are usually very small, and
they are arranged in an array having a fine pitch between
bond-pads. The dies can also be quite delicate. As a result, after
fabricating the dies, they are packaged to protect the dies and to
connect the bond-pads to another array of larger terminals that is
easier to connect to a printed circuit board. The dies can be
packaged after cutting the workpiece to separate the dies
(die-level packaging), or the dies can be packaged before cutting
the workpiece (wafer-level packaging).
Conventional die-level packaged microelectronic devices include a
microelectronic die, an interposer substrate or lead frame attached
to the die, and a molded casing around the die. The bond-pads of
the die are typically coupled to terminals on the interposer
substrate or the lead frame. In addition to the terminals, the
interposer substrate also includes ball-pads coupled to the
terminals by conductive traces supported in a dielectric material.
Solder balls can be attached to the ball-pads in one-to-one
correspondence to form a "ball-grid array." Packaged
microelectronic devices with ball-grid arrays are generally higher
grade packages having lower profiles and higher pin counts than
conventional packages using lead frames.
One process for die-level packaging includes (a) forming a
plurality of dies on a semiconductor wafer, (b) cutting the wafer
to separate or singulate the dies, (c) attaching individual dies to
an interposer substrate, (d) wire-bonding the bond-pads of the dies
to the terminals of the interposer substrate, and (e) encapsulating
the dies with a suitable molding compound. Mounting individual dies
to interposer substrates or lead frames in the foregoing manner can
be a time-consuming and expensive process. In addition, forming
robust wire-bonds that can withstand the forces involved in molding
processes becomes more difficult as the demand for higher pin
counts and smaller packages increases. The process of attaching
individual dies to interposer substrates or lead frames may also
damage the bare dies. These difficulties have made the packaging
process a significant factor in the production of microelectronic
devices.
Wafer-level packaging is another process for packaging
microelectronic devices in which a redistribution layer is formed
over the dies before singulating the dies from the workpiece. The
redistribution layer can include a dielectric layer and a plurality
of exposed pads formed in arrays on the dielectric layer. Each pad
array is typically arranged over a corresponding die, and the pads
in each array are coupled to corresponding bond-pads of the die by
conductive traces extending through the dielectric layer. After
constructing the redistribution layer on the wafer, discrete masses
of solder paste can be deposited onto the individual pads. The
solder paste is then reflowed to form small solder balls or "solder
bumps" on the pads. After forming the solder balls, the wafer is
singulated to separate the microelectronic devices, and the
individual devices can be attached to printed circuit boards or
other substrates.
Wafer-level packaging is a promising development for increasing
efficiency and reducing the cost of microelectronic devices because
individual dies are effectively "pre-packaged" with a
redistribution layer before cutting the wafers to singulate the
dies. This enables the use of sophisticated semiconductor
processing techniques to form smaller arrays of solder balls.
Additionally, wafer-level packaging is an efficient process that
simultaneously packages a plurality of dies, thereby reducing costs
and increasing throughput.
One drawback of conventional wafer-level packaged devices is that
the solder joints between the microelectronic device and substrate
are generally quite small and have a relatively short life.
Specifically, the microelectronic device and the substrate have
different coefficients of thermal expansion, and the
microelectronic device generates heat during operation. As a
result, the microelectronic device and the substrate expand at
different rates during operation, which creates stress on the
solder joints. This thermal cycling can cause the small solder
joints to fail after relatively few cycles.
One existing approach to increase the life of the solder joints
includes constructing a stack of two solder balls on each pad of
the redistribution layer. The stack of two solder balls increases
the length of the solder ball connection and, consequently, the
life of the solder joint. Specifically, this method includes
forming a plurality of first solder balls on corresponding pads of
the redistribution layer, printing a mold compound onto the
redistribution layer, and curing the mold compound. During curing,
however, the mold compound wicks up and covers the first solder
balls. As a result, the method further includes grinding the cured
mold material and a portion of the first solder balls to expose a
section of the first solder balls, and then placing a plurality of
second solder balls on corresponding first solder balls. The wafer
may include open spaces with alignment marks to assist in aligning
the second solder balls with the first solder balls.
One problem with this approach, however, is that the grinding
process scratches the first solder balls and may adversely affect
the structural integrity of the balls and the connection between
the first and second solder balls. Another problem with this
approach is that the tooling must be modified to form the open
spaces and alignment marks on the wafer each time a different
device is constructed. If the open spaces and alignment marks are
not formed on the wafer, the second solder balls may not be
accurately aligned with the first solder balls. Accordingly, there
is a need to improve the wafer-level packaging process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-7 illustrate stages in a method for manufacturing a
plurality of microelectronic devices in accordance with one
embodiment of the invention.
FIG. 1 is a schematic top plan view of a semiconductor
workpiece.
FIG. 2 is a schematic side cross-sectional view of a portion of the
semiconductor workpiece illustrated in FIG. 1.
FIG. 3 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece after forming a plurality of first
alignment marks on the protective film.
FIG. 4 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece after depositing discrete volumes of
mold compound onto the redistribution structure.
FIG. 5 is a schematic side cross-sectional view of the portion of
the workpiece and the molding apparatus after clamping the
workpiece with the first and second mold portions.
FIG. 6 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece after removing the workpiece from the
molding apparatus.
FIG. 7 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece after forming a plurality of second
interconnect elements on corresponding first interconnect
elements.
FIG. 8 is a schematic side cross-sectional view of a
microelectronic device assembly in accordance with one embodiment
of the invention.
FIG. 9 is a schematic side cross-sectional view of a portion of a
semiconductor workpiece in accordance with another embodiment of
the invention.
FIG. 10 is a schematic side cross-sectional view of a portion of a
semiconductor workpiece in accordance with another embodiment of
the invention.
FIG. 11 is a schematic illustration of a system in which the
microelectronic devices may be incorporated.
DETAILED DESCRIPTION
Specific details of several embodiments are described below with
reference to microelectronic devices including microelectronic dies
and a redistribution layer over the dies, but in other embodiments
the microelectronic devices may not include the redistribution
layer and/or can include other components. For example, the
microelectronic devices can include micromechanical components,
data storage elements, optics, read/write components, or other
features. The microelectronic dies can be SRAM, DRAM (e.g.,
DDR-SDRAM), flash-memory (e.g., NAND flash-memory), processors,
imagers and other types of devices. Moreover, several other
embodiments of the invention can have different configurations,
components, or procedures than those described in this section. A
person of ordinary skill in the art, therefore, will accordingly
understand that the invention may have other embodiments with
additional elements, or the invention may have other embodiments
without several of the elements shown and described below with
reference to FIGS. 1-11.
FIGS. 1-7 illustrate stages in a method for manufacturing a
plurality of microelectronic devices in accordance with one
embodiment of the invention. For example, FIG. 1 is schematic top
plan view of a semiconductor workpiece 100, and FIG. 2 is a
schematic side cross-sectional view of a portion of the
semiconductor workpiece 100. The illustrated semiconductor
workpiece 100 is a wafer 101 in and on which devices are
constructed. Specifically, referring only to FIG. 2, the workpiece
100 includes a substrate 110 and a plurality of microelectronic
dies 120 formed in and/or on the substrate 110. The individual dies
120 include an active side 122, a backside 124 opposite the active
side 122, a plurality of terminals 126 (e.g., bond-pads) at the
active side 122, and an integrated circuit 128 (shown
schematically) operably coupled to the terminals 126. Although the
illustrated dies 120 have the same structure, in other embodiments
the dies 120 can have different features to perform different
function.
The illustrated semiconductor workpiece 100 further includes a
redistribution structure 130 formed on the substrate 110. The
redistribution structure 130 includes a dielectric layer 132, a
plurality of traces 136 in the dielectric layer 132, and a
plurality of terminals 138 in and/or on the dielectric layer 132.
The dielectric layer 132 includes a first surface 133 facing the
active sides 122 of the dies 120 and a second surface 134 opposite
the first surface 133. The terminals 138 are exposed at the second
surface 134 of the dielectric layer 132 and electrically coupled to
corresponding terminals 126 on the dies 120 via associated traces
136. In other embodiments, such as the embodiment described below
with reference to FIG. 9, the semiconductor workpiece 100 may not
include the redistribution structure 130.
The semiconductor workpiece 100 can further include an optional
protective film 140 on the backsides 124 of the dies 120. The
protective film 140 can be a polyimide material or other suitable
material for protecting the backsides 124 of the dies 120 during
processing of the workpiece 100. In several embodiments, the
protective film 140 can be placed on the workpiece 100 before
constructing the redistribution structure 130. In other
embodiments, the workpiece 100 may not include the protective film
140.
FIG. 3 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece 100 after forming a plurality of
optional first alignment marks 144 (shown schematically) on the
protective film 140. The illustrated first alignment marks 144 are
located relative to the specific position of one or more components
on the workpiece 100 to provide a reference point for the specific
position of the components(s) from the backside of the workpiece
100. For example, the first alignment marks 144 can indicate the
position of the terminals 138 on the workpiece 100 from the
backside. The first alignment marks 144 accordingly facilitate
proper alignment of the workpiece 100 for subsequent processing.
The first alignment marks 144 can be formed by laser drilling or
other suitable processes to form a mark or other feature on the
workpiece 100. In other embodiments, the workpiece 100 may not
include alignment marks on the protective layer 140.
After marking the protective film 140, a plurality of conductive
first interconnect elements 150 are formed on corresponding
terminals 138 of the redistribution structure 130. The first
interconnect elements 150 can be solder balls or other conductive
members that project from the second surface 134 of the
redistribution structure 130. In one specific embodiment which is
not limiting, the individual first interconnect elements 150
project a distance D.sub.1 of approximately 270 .mu.m from the
redistribution structure 130. However, in other embodiments, the
first interconnect elements 150 can project a distance greater than
or less than 270 .mu.m. In either case, the individual first
interconnect elements 150 include a proximal portion 152 at the
corresponding terminal 138 and a distal portion 154 opposite the
proximal portion 152.
FIG. 4 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece 100 after depositing discrete volumes
of mold compound 160 onto the redistribution structure 130. The
illustrated volumes of mold compound 160 are deposited at
corresponding arrays of first interconnect elements 150; however,
in other embodiments, a single volume or multiple volumes of mold
compound 160 can be placed anywhere on the redistribution structure
130. After depositing the mold compound 160, the workpiece 100 is
positioned in a molding apparatus 190 that includes a first mold
portion 192, a second mold portion 194, and a release tape 196
attached to the first mold portion 192. The release tape 196 can be
a compressible member having a thickness T of approximately 100
.mu.m or another suitable thickness. In the illustrated embodiment,
the mold compound 160 is placed onto the workpiece 100 before
clamping the workpiece 100 with the first and second mold portions
192 and 194. In other embodiments, however, the first and second
mold portions 192 and 194 can clamp the workpiece 100 and then the
mold compound 160 can flow onto the workpiece 100.
FIG. 5 is a schematic side cross-sectional view of the portion of
the workpiece 100 and the molding apparatus 190 after clamping the
workpiece 100 with the first and second mold portions 192 and 194.
As the first mold portion 192 moves toward the workpiece 100, the
first mold portion 192 and the release tape 196 spread the mold
compound 160 across the second surface 134 of the redistribution
structure 130 to form a protective layer 162 on the workpiece 100.
In the illustrated embodiment, the first interconnect elements 150
are pressed into the release tape 196 such that the release tape
196 deforms and covers at least a section of the distal portion 154
of the individual first interconnect elements 150. As a result, the
illustrated protective layer 162 does not cover at least a section
of the distal portion 154 of the individual first interconnect
elements 150. Rather, the distal portions 154 are at least
partially exposed. For example, in one embodiment, the exposed
sections of the distal portions 154 project a distance D.sub.2 of
approximately 40 to 50 microns.
FIG. 6 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece 100 after removing the workpiece 100
from the molding apparatus 190. After constructing the protective
layer 162, a plurality of optional second alignment features or
marks 146 can be formed in and/or on a surface 164 of the
protective layer 162. The placement of the second alignment marks
146 can be based on the arrangement of first alignment marks 144 on
the protective film 140. The second alignment marks 146 accordingly
further facilitate proper alignment of the workpiece 100 during
subsequent processing. For example, the second alignment marks 146
may correspond to the position of the terminals 138 on the
redistribution structure 130 and assist the processing equipment in
properly positioning the workpiece 100 so that a plurality of
second interconnect elements (not shown) can be attached to
corresponding first interconnect elements 150 and properly aligned
with the terminals 138. The second alignment marks 146 may also
assist the processing equipment in properly positioning the
workpiece 100 for singulation. In other embodiments, the workpiece
100 may not include the second alignment marks 146.
After forming the second alignment marks 146, the first
interconnect elements 150 can be reshaped to facilitate attachment
of a plurality of second interconnect elements. For example, in the
illustrated embodiment, the first interconnect elements 150 are
reconfigured such that the individual distal portions 154 have a
generally flat surface 156. The generally flat surfaces 156 define
a plane that can be spaced apart from or coplanar with the surface
164 of the protective layer 162. The generally flat surfaces 156
can be formed by heating the first interconnect elements 150 and
contacting the elements 150 with a press. In the illustrated
embodiment, the first interconnect elements 150 are reshaped
without removing material from the elements 150 and the protective
layer 162. In other embodiments, however, the first interconnect
elements 150 can be reshaped with other methods, and/or the
reshaped elements may have a different configuration. In additional
embodiments, the first interconnect elements 150 may not be
reshaped. In either case, the exposed portions of the first
interconnect elements 150 can be cleaned (e.g., Ar plasma cleaned)
and fluxed before attaching a plurality of second interconnect
elements.
FIG. 7 is a schematic side cross-sectional view of the portion of
the semiconductor workpiece 100 after forming a plurality of second
interconnect elements 170 on the flat surfaces 156 of corresponding
first interconnect elements 150. The second interconnect elements
170 can be aligned with the first interconnect elements 150 based
on the first and/or second alignment marks 144 and/or 146. In other
embodiments, the second interconnect elements 170 can be aligned
with the first interconnect elements 150 via other suitable
methods. In either case, after forming the second interconnect
elements 170, the semiconductor workpiece 100 can be heated to
reflow the first and second interconnect elements 150 and 170 so
that the elements 150 and 170 form a robust connection. After
reflowing the first and second interconnect elements 150 and 170,
the semiconductor workpiece 100 can be cut along lines A-A to
singulate a plurality of individual microelectronic devices
102.
FIG. 8 is a schematic side cross-sectional view of a
microelectronic device assembly 104 in accordance with one
embodiment of the invention. The illustrated device assembly 104
includes a singulated microelectronic device 102 and a substrate
180 attached to the device 102. The substrate 180 can be a printed
circuit board or other member having a plurality of pads 182
arranged in an array corresponding to the array of second
interconnect elements 170 so that the second interconnect elements
170 can be attached to corresponding pads 182.
The embodiment of the microelectronic device assembly 104
illustrated in FIGS. 1-8 includes stacks of two interconnect
elements 150 and 170 connecting the terminals 138 on the
microelectronic device 102 to the pads 182 on the substrate 180.
The individual stacks of first and second interconnect elements 150
and 170 increase the length of the joint between the
microelectronic device 102 and the substrate 180. The increased
length of the joint is expected to increase the life of the joint
and the microelectronic device assembly 104 because the joint life
is related to the von-Mises creep strain energy density and a
longer joint reduces the strain energy density in the joint.
The embodiment of the method for manufacturing the microelectronic
devices 102 illustrated in FIGS. 1-7 does not need to remove
material from the first interconnect elements 150 or the protective
layer 162 via grinding or other abrasive techniques. As a result,
the first interconnect elements 150 and the protective layer 162
are expected to have greater structural integrity, which increases
the yield of the microelectronic devices 102.
The embodiment of the method for manufacturing the microelectronic
devices 102 illustrated in FIGS. 1-7 includes optionally forming
the first alignment marks 144 on the protective film 140 and the
second alignment marks 146 on the protective layer 162. The first
and second alignment marks 144 and 146 facilitate alignment of the
semiconductor workpiece 100 so that the second interconnect
elements 170 can be precisely positioned on corresponding first
interconnect elements 150 and the individual microelectronic
devices 102 can be accurately singulated. Moreover, the first and
second alignment marks 144 and 146 need not be formed in an open
space at a specific location on the workpiece 100. As a result, the
space available on the workpiece 100 for active devices is
increased, and the tooling used in constructing the workpiece 100
need not be modified to construct different microelectronic
devices.
The embodiment of the microelectronic device assembly 104
illustrated in FIG. 8 includes a protective layer 162 covering the
proximal portions 152 of the first interconnect elements 150 and
the surface 164 of the redistribution structure 130. The
illustrated device assembly 104 does not include an underfill
material between the protective layer 162 of the microelectronic
device 102 and the substrate 180. The device assembly 104 need not
include an underfill material because the protective layer 162
provides sufficient support to the first interconnect elements 150
and adequate protection to the redistribution structure 130.
In one embodiment, a method of forming a plurality of
microelectronic devices on a semiconductor workpiece includes
placing a plurality of first interconnect elements on a side of a
semiconductor workpiece, forming a layer on the side of the
workpiece, reshaping the first interconnect elements by heating the
first interconnect elements, and coupling a first portion of a
plurality of individual second interconnect elements to
corresponding first interconnect elements with a second portion of
the individual second interconnect elements exposed.
In another embodiment, a method includes forming a plurality of
first interconnect elements on corresponding terminals of a
semiconductor workpiece, molding a layer onto the workpiece with
the layer covering only a portion of the first interconnect
elements, and attaching a plurality of free second interconnect
elements to corresponding first interconnect elements.
In another embodiment, a method includes constructing a plurality
of first interconnect elements on corresponding terminals of a
semiconductor workpiece, reconfiguring the first interconnect
elements without removing material from the first interconnect
elements, and, after reconfiguring the first interconnect elements,
placing a plurality of second interconnect elements on
corresponding first interconnect elements. The individual second
interconnect elements including a first portion attached to the
corresponding first interconnect element and a second portion
exposed.
In another embodiment, a method includes constructing a
redistribution structure on a first side of a semiconductor
workpiece, providing an alignment feature on a second side of the
workpiece, forming a plurality of first interconnect elements on
the redistribution structure with the first interconnect elements
projecting from the redistribution structure, reconfiguring the
first interconnect elements, and aligning a plurality of free
second interconnect elements with corresponding first interconnect
elements based on the alignment feature.
In still another embodiment, a semiconductor workpiece includes a
substrate and a plurality of dies formed at the substrate. The
individual dies include an integrated circuit and a plurality of
terminals operably coupled to the integrated circuit. The workpiece
further includes a plurality of first interconnect elements
electrically coupled to corresponding terminals, a protective layer
having a first surface facing the substrate and a second surface
opposite the first surface, and a plurality of stacked second
interconnect elements attached to corresponding first interconnect
elements. The individual first interconnect elements have a
proximal portion proximate to the substrate and a distal portion
opposite the proximal portion. The distal portion of the individual
first interconnect elements projects from the second surface of the
protective layer.
In yet another embodiment, a semiconductor workpiece includes a
substrate and a plurality of dies formed at the substrate. The
substrate has a first side and a second side opposite the first
side. The individual dies include an integrated circuit and a
plurality of terminals operably coupled to the integrated circuit.
The workpiece further includes a plurality of first interconnect
elements at the first side of the substrate and electrically
coupled to corresponding terminals, a plurality of stacked second
interconnect elements attached to corresponding first interconnect
elements, and an alignment feature on the second side of the
substrate.
FIG. 9 is a schematic side cross-sectional view of a portion of a
semiconductor workpiece 200 in accordance with another embodiment
of the invention. The illustrated workpiece 200 is generally
similar to the workpiece 100 described above with reference to
FIGS. 1-7. For example, the illustrated workpiece includes a
substrate 210, a plurality of microelectronic dies 220 formed in
and/or on the substrate 210, a plurality of first interconnect
elements 150, and a plurality of second interconnect elements 170
attached to corresponding first interconnect elements 150. The
illustrated workpiece 200, however, does not include a
redistribution structure. Rather, the first interconnect elements
150 are attached directly to the terminals 126 of the
microelectronic dies 220. The terminals 126 on the dies 220 are
accordingly spaced apart such that the adjacent stacks of first and
second interconnect elements 150 and 170 do not contact each
other.
FIG. 10 is a schematic side cross-sectional view of a portion of a
semiconductor workpiece 300 in accordance with another embodiment
of the invention. The illustrated workpiece 300 is generally
similar to the workpiece 100 described above with reference to
FIGS. 1-6. For example, the workpiece 300 includes a substrate 110,
a plurality of dies 120 formed in and/or on the substrate 110, a
redistribution structure 130 formed on the dies 120, and a
plurality of first interconnect elements 150 attached to
corresponding terminals 138 of the redistribution structure 130.
The illustrated individual first interconnect elements 150,
however, include a coating 358 covering the proximal portion 152,
but not the distal portion 154. The coating 358 can have a first
surface tension, and the first interconnect elements 150 can have a
second surface tension greater than the first surface tension. The
difference in the first and second surface tensions enables the
protective layer 162 to be formed by methods other than molding.
Specifically, when a flowable compound is deposited onto the
redistribution structure 130, the coating 358 inhibits the flowable
compound from wicking up the first interconnect elements 150 and
covering the distal portions 154. As a result, the protective layer
162 can be formed by spin-on, printing, dispensing, or other
suitable methods. In other embodiments, the coating 358 may cover
the proximal and distal portions 152 and 154 of the individual
first interconnect elements 150. For example, the distal portion
154 of the individual first interconnect elements 150 may be
covered with sacrificial coating, and after forming the protective
layer 162, the sacrificial coating can be removed with any portion
of the protective layer 162 that covers the distal portion 154.
Any one of the microelectronic devices described above with
reference to FIGS. 1-10 can be incorporated into any of a myriad of
larger and/or more complex systems 490, a representative one of
which is shown schematically in FIG. 11. The system 490 can include
a processor 491, a memory 492 (e.g., SRAM, DRAM, Flash, and/or
other memory device), input/output devices 493, and/or other
subsystems or components 494. Microelectronic devices may be
included in any of the components shown in FIG. 11. The resulting
system 490 can perform any of a wide variety of computing,
processing, storage, sensor, imagers and/or other functions.
Accordingly, representative systems 490 include, without
limitation, computers and/or other data processors, for example,
desktop computers, laptop computers, Internet appliances, hand-held
devices (e.g., palm-top computers, wearable computers, cellular or
mobile phones, personal digital assistants), multi-processor
systems, processor-based or programmable consumer electronics,
network computers, and mini computers. Other representative systems
490 include cameras, light or other radiation sensors, servers and
associated server subsystems, display devices, and/or memory
devices. In such systems, individual dies can include imager
arrays, such as CMOS imagers. Components of the system 490 may be
housed in a single unit or distributed over multiple,
interconnected units, e.g., through a communications network.
Components can accordingly include local and/or remote memory
storage devices, and any of a wide variety of computer-readable
media.
From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the spirit and scope of the invention.
For example, many of the elements of one embodiment can be combined
with other embodiments in addition to or in lieu of the elements of
the other embodiments. Accordingly, the invention is not limited
except as by the appended claims.
* * * * *